Bag making machine with adjustable gears

ABSTRACT

A machine for making bags from strips of thermoplastic material whereby the strip, either longitudinally overfolded or tubular, is passed from a supply roll over an impression roller where it is momentarily contacted by a heated blade means, which severs and seals along a line of seal to form the bags. The heated blade means is preferably in the form of an integral unit having two oppositely-extending blade portions. The blade means is rotated to bring the blade portions into alternate contact with the strip so that one complete rotation of the blade means forms two bags. The blade means is mounted on a shaft which is actuated by an elliptical gear assembly so that there is a variation in the speed of rotation of the blade means, Between the elliptical gear assembly and the shaft on which the blade means is mounted is a simple manual worm assembly to vary the rotational speed of the blade means as desired, and, thereby, various sizes of bags can be produced.

United States Patent 1 Membrino BAG MAKING MACHINE WITH ADJUSTABLE GEARS[76] Inventor: Hercules Membrino, 1934 Arch St.,

Philadelphia, Pa. 19103 [22] Filed: Dec. 9, 1971 [211 App]. No.: 206,475

Related US. Application Data [63] Continuation-impart of Ser. No.136,862, April 23, 1971, which is a continuation-in-part of Ser. No.

874,523, Nov. 6, 1969, Pat. No. 3,616,095.

52 us. Cl. .l 156/515, 156/582 [51] Int. Cl B32b 31/00 [58] Field ofSearch 156/515, 582.3, 251, 156/359 [56] References Cited UNITED STATESPATENTS 3,053,723 9/1962 Plach et a1. 156/515 3,083,757 4/1963 Kraft eta1 156/515 3,360,416 12/1967 Cochrane.. 156/359 3,492,190 l/1970Poncy... 156/583 3,522,135 7/1970 Page 156/251 Y [111 3,755,041 [45']Aug. 28, 1973 Primary Examiner-Douglas J. Drummond Attorney-Arthur A.Jacobs et a1.

[5 7] ABSTRACT A machine for making bags from strips of thermoplas-- ticmaterial whereby the strip, either longitudinally overfolded or tubular,is passed from a supply roll over an impression roller where it ismomentarily contacted by a heated blade means, which severs and sealsalong a line of seal to form the bags. The heated blade means ispreferably in the form of an integral unit having twooppositely-extending blade portions. The blade means is rotated to bringthe blade portions into alternate contact with the strip so that onecomplete rotation of the blade means forms two bags. The blade means ismounted on a shaft which is actuated by anlelliptical gear assembly sothat there is a variation in the speed of rotation of the blade means,Between the elliptical gear assembly and the shaft on which the blademeans is mounted is a simple manual worm assembly to vary the rotationalspeed of the blade means as desired, and, thereby, various sizes of bagscan be produced.

7 Claims, 7 Drawing Figures Patented Aug. 28, 1973 3 Sheets-Shet 1[llliilll llllllllllllll Patented Aug; 28,1973

3 Sheets-Sheet 2 Patented Aug. 28, 1973 3,755,041

3 Sheets-Sheet 5 -1 BAG MAKING MACHINE WITH ADJUSTABLE GEARS This is acontinuation-in-part of co-pending U.S. Pat. application Ser. No.136,862, filed Apr. 23, 1971, which is, in turn, a continuation-in-partof U.S. Pat. application Ser. No. 874,523, filed Nov. 6, 1969, andissued as Pat. No. 3,616,095 on Oct. 26, 1971.

This invention relates to a machine for making bags from thermoplasticmaterial, and it particularly relates to a machine of this type which iscapable of making bags of various sizes.

Machines of this type generally comprise a supply roll of thermoplasticstrip material of double-ply construction, that is, eitherlongitudinally overfolded sheet material or tubular material, from whichthe strip is passed over an impression roller. As it passes over theimpression roller, a heated knife, wire or the like, is passed intomomentary contact with the strip to simultaneously form a line of sealand to sever the strip along the line of seal, thereby forming a seriesof bags. The heated knife or wire was, generally, mounted on a rotatablecylindrical head which rotated in synchronism with the impression rollerso that a predetermined length of strip would pass around the impressionroller between each contact by the heated knife or wire, thereby formingbags of predetermined size.

One disadvantage of these prior machinesv was the fact that they couldonly make one size of bags unless the machine was stopped and taken outof service, so that different parts, such as the sealing head, gears,'etc., could be substituted for the original parts.

Another disadvantage of these prior machines was that they weregenerally provided with means, such as masking strips covering smallportions of the knife or wire, or recesses in the knife or wire, orsimilar means, which prevented passage of sufficient heat to sever thestrip of those areas. This formed so-called nips or connections betweenthe otherwise separated bags. One reason for the formation of thesenips" was to enable the bags to remain in a strip for packaging, fillingor other purposes. However, even when it was not desirable to retain thebags in a strip, it was still necessary to do so because thethermoplastic bags have a tendency to stick to the heated knife or wire,but by retaining the bags in a strip and by maintaining a constanttension on the strip during its forward movement, the bags were pulledaway from the heating means and this sticking tendency was overcome.However, this requirement for forming connecting nips required theprovision of extra mechanical parts and. labor which could be eliminatedif the necessity of having nips could be eliminated. I

One object of the present invention is to overcome the above and otherdisadvantages of prior machines of this type by providing a bag makingmachine which can be easily adjusted, with little interruption in itsoperation, to make different sized bags.

Another object of the present invention is to provide a continuousmotionbag making machine of the aforesaid type which eliminates thenecessity of forming connecting nips" between the bags in order toprevent sticking to the heated sealing and severing means.

Other objects and many of the attendant advantages of this inventionwill be readilyappreciated as the same becomes better understood byreference to the following description when read in conjunction with theaccompanying drawings wherein:

FIG. 6 is a perspective. view of the elliptical gears.

FIG. 7 is an enlarged, detailed, perspective view of the sealing head.

Referring now in greater detail to the drawings wherein similarreference characters refer to similar parts, there is shown a machine,generally designated 10, comprising'a pair of oppositely-disposed wallsor side plates 12 'and 14 between which extends a drive shaft 16operated by an electric motor 18 through an endless drive chain 20movable around sprocket 22 on the motor shaft and sprocket 24 on thedrive shaft 16. Also mounted on the drive shaft 16, adjacent theexternal surface of plate 12, is a change gear 26. The change gear 26 isremovably connected to the shaft 16 so that it may be easily replaced byother similar change gears of different sizes in accordance with thedesired speed of the impression'roller which, in turn, affects the sizeof the bags. v

The change gear 26 is in mesh with an intermediate idler gear 28 whichis mounted for rotation on a stub shaft 30 which is supported by arocker arm 32. The rocker arm 32 is connected at its upper end to arotatable shaft 34 which'supports the impression roller 36. The mountingof the gear 28 on the rocker arm 32 is to permit the gear 28 to beadjusted relative to the change of gear 26 so that it is alwaysmaintained in mesh therewith regardless of the size of the change gear.Any'desired standard means may be used to retain the rocker arm inadjusted position. One such means may take the form of a lock screw andslot connection (not shown) between the rocker arm 32 and the wall 12,such as shown, for example, in U.S. Pat. No. 3,233,527.

The idler gear 28 is also in mesh with a gear 38 mounted on the shaft34, the gear 38 acting to rotate the shaft 34. The rotation of the shaft34 may be varied somewhat, however, by means of a differential gearmechanism which includes the worm gear 40 mounted on the shaft 34coaxially with the gear 38. The worm gear 40 and a plurality of piniongears 42 are all mounted on a disc which rides freely on shaft 34. Thesepinion gears 42 are in mesh with a beveled gear 44 on one side of thegear 40 and a beveled gear 46 on the opposite side of gear 40. The gearis connected to gear 38 by asleeve 48 which rides freely on the shaft34, while the gear 46 is pinned to the shaft 34, as indicated at 50.When the gear 40 is rotated to move the pinion gears 42 in the samedirection as the rotation of the shaft 34, this causes the gear 46 torotate in the oppositedirection, thereby slowing down the rotation ofthe shaft 34 and, consequently, of the impression roller 36. If the gear40 is rotated in the opposite direction, the speed of rotation of shaft34 is increased. This differential gear assembly is a standard typemechanism which is generally disclosed, for example, in U.S. Pat. No.3,233,527.

The gear 40 is actuated by a worm 52 mounted on a shaft 54 operativelyconnected to an electrical motor 56. The motor 56 is actuated by anelectric eye assembly, indicated at 58 in FIG. 1. This electric eyemechanism is also of a standard type and its structure and operativeconnection to the motor 56 may be of any desired arrangement. An exampleof such arrangement is disclosed in greater detail in the aforementionedU.S.

Pat. No. 3,233,527. A manually operable disc 60 is connected to theupper end of the shaft 54. This disc can be rotated by hand to obtainfaster adjustment or greater adjustment than is obtainable by means ofthe electric eye mechanism.

The electric eye mechanism may be used in conjunction with spots orother printed matter on the strip, and is used to compensate forvariation of the printed matter due to shrinking or stretching of thestrip material. In this respect, the strip material may be imprintedwith advertising or other indicia which is so placed that the design isrepeated for each area which is to correspond to an individual bag.Since the material is stretchable, the indicia may move out of registerwith the heated sealing means so that the lines of seal would cutthrough the printing. The electric eye mechanism detects such variationsin that when it detects the printing in the wrong place, it closes aswitch and activates the motor 56 which, in turn, activates thedifferential gear mechanism described above, moving the impressionroller faster or slower as called for by the electric eye.

The plastic strip material 62, either overfolded sheet stock or tubularstock, (both types being generically referred to as double-plymaterial), is supplied from a 'roll thereof designated 63 mounted on aremovable spool 64. The strip is initially threaded under a draw roller65, which is driven in synchronism with the shaft 34 by gears 66 and 67,or by any other desirable means,

over the impression roller 36, and under a sealing head 68.- It is alsooptionally held against the impression roller 36 by an idlerpresserroller 70. As the impression roller and draw roller thereafter rotate,the strip 62 is drawn from thesupply roll 63.

The impression roller 36 is provided with a series of laterally spacedgrooves 72 (see FIG. 4) within which are arranged endless belts or tapes74. These tapes 74 also extend around roller 76 on a shaft 78 and areused primarily to prevent sticking and wrapping around of the plasticstrip on the impression roller 36. Although relatively wide tapes areillustrated, narrow tapes or chains may be subtituted if desired. Alsomounted on shaft 78 are rollers which support endless belts 80 inconjunction with similar rollers mounted on a shaft 82. The belts coactwith similar belts 84 extending between rollers on shafts 85 and 86, thetwo endless belts acting as conveying means for the completed bags. Theconveyor belts are driven by an endless chain 87 extending between asprocket 88 on shaft 34 and a sprocket 89 on the tending between asprocket 88 on shaft 34 and a sprocket 89 on the shaft 85.

The sealing head 68 is best illustrated in FIG. 4 and 7 and comprises apair of oppositely disposed blades 90 constructed of metalor other heatconducting substance. The blades, including the heating elements latingstrip 96 by any desirable means such as bolts, clamps, adhesive, etc.,these strips 96 being provided in order to reduce heat transfer to theshaft 94. Heat is supplied to the blades by electrical heating elements98 positioned in corresponding bores in the respective blades 90. Theseheating elements are in electrical circuit with a source of electricalenergy through any desired standard means such as flexible cables,commutators, or the like. 7

The provision of two opposed blades pennits the formation of two bagsduring each complete rotation of the sealing head.

Another feature inherent in this construction is that there is such arapid movement of the blades immediately after contact between theblades and the strip that the blades break away from the strip before itcan stick to them. Futhermore, the rapid movement of the blades actuallyacts to kick the severed bags away from the strip and onto the conveyor.In this manner, the necessity for having nips to permit the formed bagsto be pulled away from the sealing head is obviated.

The shaft 94 is rotatably mounted between a pair of bearing blocks 100which are vertically slidable in corresponding guideways 102 on therespective wall 12 and 14. The blocks 100 are adjustable toward and awayfrom the impression roller 36 by means of screws 104 (see FIGS. 1 and 2)which extend through corresponding blocks 106. Each screw is held inadjusted position by a nut 108.

Mounted on the shaft 94 is a sprocket which is driven by an endlesschain'll2 from a sprocket I14 freely rotatable on the shaft 34. Thechain 112 is held in tension by a spring-pressed idler sprocket 116which permits adjustment of the chain as the shaft 94 is verticallyadjusted.

An oval or double lobe elliptical gear 1 18 is mounted on the driveshaft 16 (note FIGS. 3 and 5). The gear 1 18 is in mesh with a secondoval or elliptical gear 120. The gear l20 is mounted on a bushing 122which is freely slidable and rotatable on the shaft 34. The gear isconnected, as by means of screws 124 or the like, to a bevel gear 126which is also mounted on the bushing 122. Adjacent the bevel gear 126,mounted on a freely rotatable bushing 128, is a worm gear 130. Connectedto the gear 130 are a plurality of pinion gears 132. These pinion gears132 are in mesh with both the bevel gear 126 and a second bevel gear 134on the opposite side of the worm gear 130 and in opposed relation to thebevel gear 126. The bevel gear 134 is also mounted on and independentlyrotatable bushing 136 and is connected, as by screws 138 or the like, tothe sprocket 114, which is, itself, mounted on the bushing 136. A worm142 is in mesh with the worm gear 130, this worm 142 being mounted on ashaft 144 which is rotatable by a manually-operable disc handle 146.

The elliptical nature of the gears 1 l8 and 120 permits a variation inthe speed of rotation whereby the two end portions, or end lobes, of thegears effect a more rapid movement than the side portions between thelobes. Therefore, the end lobes of the gears cause a relatively rapidmovement of the corresponding blades of the sealing head into and out ofcontact with the thermoplastic strip, while the sides of the gears causea relatively slower movement of the blades.

A previously indicated, the rotational or surface speed of theimpression roller 36 may be varied by varying the size of the changegear 26. Heretofore,

. 5' when this was done, it was also necessary to change the sealinghead assembly to make it larger or smaller to correspond to thevariation'in speed of the impression roller. By means of the presentinvention, the necessity for this replacement of the sealing headassembly is eliminated.

When the high lobesof gear 118 meet the low lobes of gear 120, shaft 94is rotating at a fast speed, when the low lobes of gear 118 meet thehigh lobes of gear 120, shaft 94 rotates at a slower speed. Therefore,with the use of elliptical gears, shaft 94 is rotated at various speedsbetween the high and low lobes of gear 1 18 with each revolution ofdrive shaft 16.

Drive shaft 16 also drives the impression roller 36 through change gear26. As different change gears are used, the impression roller 36 rotatesat different surface speeds.

By setting the position of the sealing blades to the correspondingposition of the gear ratio on the elliptical gears 118 and 120 equal tothe change gear, the surface speed of both the impression roller 36 andthe sealing blades 98 are in harmony.

The selection of the correct position of the sealing bladescorresponding to the gear ratio on the elliptical gears is accomplishedby the differential mechanism which is positioned between them. Byrotating worm 142, which moves gear 130 and pinion gears 132, bevel gear134 and sprocket 114 will speed up or slow down, changing the positionof the sealing blades 98 relative to the position of the end lobes ofthe elliptical gears 118 and 120. The selection of the proper gear ratioof the elliptical gears 1 l8 and 120 that is required in order to havethe surface speed of the sealing blades 98 match the surface speed ofthe impression roller 36, may be made by trial and error method.Thisrequires the stopping of the machine, disengaging sprocket 110 fromshaft 94, turning shaft 94 forward or backward as an estimatedadjustment, engaging sprocket 110 to shaft 94, and running the machineto test. This method could require several adjustments.

However, with the use of the differential mechanism, not stopping ordown time is needed when change gear 26 is replaced with a differentsize gear to make a differnt size bag. The correct and accurate ratioselection is made at once by turning worm 142 while the machine is inmotion. q

Although the elliptical gear differential assembly and the sprocket 114are here illustrated as being mounted for independent rotation on thesahft 34, it is to be understood that this is merely for convenience andsimplicity because the shaft 34 acts merely as a supporting means. Ifdesired, these elements maybe mounted on I a separate stub shaftconnected to a side plate of the machine in an ofiset relationshiprelative to the shaft 34.

It is to be noted that although the sealing head 68 is illustrated as anintegral unit with oppositely-disposed blade portions, and although thisillustrated form is the preferred form, it is also possible to use othertypesof sealing heads, as, for example, a cylinder with spaced knifeblades, ribbons, wires, or the like on tis periphery, the term strips"being used to generically describe such ribbons, wires or the like. Itis also possible to utilize the form of the device shown in FIG. 5 butto make the ends somewhat flatter and to stretch wires therealong, thesewires acting as the sealing and severing means.

The invention claimed is:

l. A bag making machine comprising a supply means for supplying a stripof double-ply thermoplastic material, a rotatable impression roller, afirst drive means operatively connected to said impression roller torotate said impression roller, a first speed varying means operativelyconnected to said first drive means for varying the speed of rotation ofsaid impression roller, a rotatable heated sealing and severing means, asecond drive means operatively connected to said sealing and severingmeans to rotate said sealing and severing means,,and a second speedvarying means operatively connected to said second drive means forvarying the speed of rotation of said sealing and severing means incorrelation with the speed of surface rotation of said impressionroller, said various means being operatively connected to each other andbeing constructed and arranged to pass said strip from said supply meansover said impression roller, said impression roller supporting saidstrip while said sealing and severing means, during rotation thereof,impacts said strip to form lines of seal and severance which are spacedfrom each other by a predetermined distance longitudinally of saidstrip.

2. The machine of claim lwherein said second drive means comprises adrive shaft having a first elliptical gear mounted thereon, a secondelliptical gear in mesh with said first elliptical gear, said secondelliptical gear being operatively connected to an actuating means whichis operatively connected to said sealing and severing means for rotatingsaid sealing and severing means, and a differential gear assemblyoperatively connected between said second elliptical gear and saidactuating means, said differential gear assembly comprising said secondspeed varying means.

3. The machine of claim 2 wherein said differential gear assemblycomprises a worm gear having at least one pinion gear connected thereto,said pinion gear being in mesh with oppositely-disposed bevel gears, oneon each side of the worm gear, one of said bevel gears being connectedto said second elliptical gear and the other bevel gear being connectedto said actuating means, and adjusting means for adjusting both saiddifferential gear assembly and the radial positions of said ellipticalgears.

4. The machine of claim 3 wherein said adjusting means is a worm inmeshwith said worm gear, said worm being mounted on a worm shaft, and amanuallyoperable handle operatively connected to said worm shaft.

5. The machine of claim 1 wherein said sealing and severing ,meanscomprises at least two oppositelydisposed heated severing elements.

6. The machine of claim 5 wherein said sealing and severing elements areheated blades extending radially from a rotatable hub portion.

7. The machine of claim 5 wherein said sealing and severing elements areheated strips.

* i i i

1. A bag making machine comprising a supply means for supplying a stripof double-ply thermoplastic material, a rotatable impression roller, afirst drive means operatively connected to said impression roller torotate said impression roller, a first speed varying means operativelyconnected to said first drive means for varying the speed of rotation ofsaid impression roller, a rotatable heated sealing and severing means, asecond drive means operatively connected to said sealing and severingmeans to rotate said sealing and severing means, and a second speedvarying means operatively connected to said second drive means forvarying the speed of rotation of said sealing and severing means incorrelation with the speed of surface rotation of said impressionroller, said various means being operatively connected to each other andbeing constructed and arranged to pass said strip from said supply meansover said impression roller, said impression roller supporting saidstrip while said sealing and severing means, during rotation thereof,impacts said strip to form lines of seal aNd severance which are spacedfrom each other by a predetermined distance longitudinally of saidstrip.
 2. The machine of claim 1 wherein said second drive meanscomprises a drive shaft having a first elliptical gear mounted thereon,a second elliptical gear in mesh with said first elliptical gear, saidsecond elliptical gear being operatively connected to an actuating meanswhich is operatively connected to said sealing and severing means forrotating said sealing and severing means, and a differential gearassembly operatively connected between said second elliptical gear andsaid actuating means, said differential gear assembly comprising saidsecond speed varying means.
 3. The machine of claim 2 wherein saiddifferential gear assembly comprises a worm gear having at least onepinion gear connected thereto, said pinion gear being in mesh withoppositely-disposed bevel gears, one on each side of the worm gear, oneof said bevel gears being connected to said second elliptical gear andthe other bevel gear being connected to said actuating means, andadjusting means for adjusting both said differential gear assembly andthe radial positions of said elliptical gears.
 4. The machine of claim 3wherein said adjusting means is a worm in mesh with said worm gear, saidworm being mounted on a worm shaft, and a manually-operable handleoperatively connected to said worm shaft.
 5. The machine of claim 1wherein said sealing and severing means comprises at least twooppositely-disposed heated severing elements.
 6. The machine of claim 5wherein said sealing and severing elements are heated blades extendingradially from a rotatable hub portion.
 7. The machine of claim 5 whereinsaid sealing and severing elements are heated strips.